looking at the data I think I figured out a bit more!
command sent: 6C 1A F1 19 11 FF 11
6C = node to node GM message
1A = address of TCCM
F1 = address of scanner
19 = Request Diagnostic Trouble Codes by Status (14 should clear codes)
11 = (should have sent C2) 11 = MIL is illuminated and Immature code.
FF = send to all groups (not sure why 40 chassis doesn't work)
how to read the code:
6C F1 1A 59 XZ ZZ YY [last byte checksum?]
the X is the first part of the code
4 = C0
8 = B0
A = B2
D = U1
ZZZ = code
(for complete code put together XZZZ)
the YY appears to be the status of the code where
01 - good - no issue
93 - current code
11 - not sure yet
if you send the command 6C 1A F1 19 11 FF 11, look at the before last byte on each row, any that are NOT 01 are worth a look at.
one step closer to folks being able to read 4WD service codes at home